The present invention relates to a valve for removing trapped air from a pump line and relates particularly, although not exclusively, to a valve for removing trapped air from pump lines of tankers.
When unloading tankers, especially milk tankers, a lot of milk is lost whenever the line from the tanker is coupled to a pump. The loss results from the priming of the pump and may be in the order of 6 to 8 pints. The air must be removed from the line and usually the milk is allowed to escape until the pump is primed. With the tightening of pollution controls, means are now required to eliminate such waste and prevent the fatty substances contained in the milk from entering drains which may discharge into rivers, etc.
In one solution to this problem a valve device is coupled to a T-piece connection in the pump line. The valve consists of a tube with a spherical portion intermediate thereof. A ball valve is contained within the spherical portion and in the closed position covers the lower-most valve seat formed by the interface between the tube and the spherical portion. Air may escape by displacing the ball valve and allowing air to pass through the spherical portion and to exit through the opposing open end of the tube. When the air has escaped the ball valve will be forced up into the uppermost position to prevent air entering the pump line. The problem with this type of valve is that it is extremely difficult to clean and air may enter the valve under fattening pressure.